Analysis of the favorability for geothermal fluid flow in 3D: Astor Pass geothermal prospect, Great Basin, northwestern Nevada, USA

Abstract

As geothermal exploration increasingly focuses on blind or hidden systems, precise geologic characterization of the sub-surface at potential development sites becomes essential. Geothermal circulation requires elevated heat, relatively high permeability, and ample fluid flow. Evidence for the collocation of these characteristics occur in areas where geothermal circulation is most likely to occur and where exploration activities should be focused. Employing a 3D geologic framework constructed through integration of many separate datasets, we demonstrate a methodology for analyzing the data types that can be used as proxies for these three key characteristics. This methodology is applied at the Astor Pass geothermal prospect in northwestern Nevada, western USA. Based on geologic structure modeled in 3D, several proxies for heat, fluids and permeability are compared in order to identify areas within the field with the highest favorability for geothermal fluid flow. Geological and conceptual models constructed through these methodologies can be used to develop exploration strategies and subsequently site wells. Such models can be iteratively adapted with newly acquired data, as prospects evolve into mature geothermal developments. If developed prior to expensive drilling programs, these techniques allow for more efficient use of limited drilling budgets, ultimately lowering the risks and costs of geothermal exploration and development.